Voltage regulator



y 27, 1958 H. FRIEDMAN 2,836,727

VOLTAGE REGULATOR Filed Aug. 4, 1955 HM T //.M

- IN V EN TOR. HERBERT FRIEDMAN AGEN T.

nite 1 My invention relates to a device for controlling the potential of a high-voltage source.

More specifically, my invention relates to a device for controlling the potential of a source employing secondary X-radiation produced by exposing samples of chemical elements to primary X-radiation produced by an X-ray tube connected to the source of potential which is subject to control.

Every element of the periodic series emits characteristic secondary X-radiation when exposed to a primary beam of X-radiation of sufiiciently short wave length. If the spectrum of the primary X-radiation contains wave lengths shorter than the absorption edge of that element, the intensity of its characteristic radiation will increase rapidly as the intensity of the primary radiation at those wave lengths increases. Thus, by utilizing characteristic secondary X-radiation rather than primary X-radiation, it is possible to control the voltage of a source within narrow limits.

It is accordingly a principal object of my invention to provide a novel apparatus for controlling the potential of a voltage source by means of the characteristic secondary X-radiation produced by an element exposed to primary radiation having a wave length below the absorption edge of that element.

It is a further object of my invention to provide a novel apparatus for controlling the potential of a voltage source within narrow limits.

These and further objects of my invention will appear as the specification progresses.

In accordance with my invention, I expose a sample containing at least one element to primary X-radiation produced by a tube energized by the voltage source the potential of which is to be stabilized. This element is selected so that the primary X-radiation from the tube will excite at least one element in the sample to emit its characteristic spectrum. The sample may also contain a second element so low in atomic number that its characteristic lines are totally absorbed in air, or suficiently higher in atomic number that no characteristic lines are excited which can be detected. These samples will hereinafter be referred to as secondary radiators since they produce secondary or characteristic X-radiation upon exposure to primary X-radiation from the tube.

As the voltage applied to the X-ray tube varies, the intensity of the characteristic X-radiation of the first element will vary as the square of the difierence in applied voltage while the second element only will scatter the primary radiation. Thus, by suitably detecting and converting the X-radiation produced by the respective elements into appropriate electrical quantities, corrective measures can be taken to compensate for the variations in potential of the source.

The invention will be described in connection with the accompanying drawing which shows a voltage stabilizing device according to the invention.

In the embodiment of the invention shown in the drawing, cathode 1 and anode 2 of an X-ray tube 3, which rates Patent serves as a source of primary X-radiation for the invention as well as other purposes, are connected to a' line source of voltage 4 through a transformer 5.

In the path of a portion 9 of the X-radiation, I expose secondary radiators 10 and 11 of, for'example, silver and molybdenum respectively, which emit secondary X-' radiation when exposed to the primary X-radiation. The molybdenum will not emit its characteristic X-radiation if the voltage applied to the X-ray tube is less than 20 tensity increases only slightly as the voltage applied tothe tube increases above 20 kv.

Thus, an increase of 2 kv. in the voltage applied to the X-ray tube will result in a 109% increase in intensity of the lVIOKu radiation and a 5% increase in the X-radiatiou from the silver sample.

A portion of this characteristic X-radiation of the two secondary radiators is intercepted by collimators 12 and 13 respectively and is directed into detectors 14 and 15 respectively. These detector are shown as conventional Giger-Muller tubes having a central anode 16 and a concentric cathode 17, connected to a source of high voltage, the tube being filled with an ionizable medium. Alternatively, a scintillation counter, proportional counter, ionization chamber or similar detection device which will convert X-ray quanta into electrical pulses, may be used. The outputs of the detectors are shown connected to a conventional bridge circuit 18 for deriving an electrical quantity proportional to the difference in outputs of the respective detectors. Connected between the mid-points of the bridge is an electric motor 19 mechanically coupled to the moveable arm of a variable autotransformer 20 in the line source. Alternatively, a conventional errorcorrecting system connected to the outputs of the detectors could be employed to compensate for variations in line voltage.

Any element of the periodic table may be employed as a secondary radiator to control the voltage applied to the tube. At higher operating potentials, heavier elements such as uranium which emits its characteristic radiation only when the potential applied to the tube exceeds kv. may be employed.

While I have thus described my invention with specific examples and applications, other modifications will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A device for controlling the potential of a source comprising an X-ray tube coupled to said source, a secondary radiator containing at least one element of the periodic series which when exposed to X-radiation pro-- duced by said tube generates its characteristic X-ray spectra, means to detect the characteristic X-ray radiation produced by said secondary radiator, and means,

coupled to said detection means and responsive to the intensity of the characteristic radiation produced by said element for controlling the potential of said source.

2. A device for controlling the potential of a sourcecomprising an X-ray tube coupled to said source, a secondary radiator exposed to primary X-radiation produced by said tube and containing an element which generates. its characteristic X-radiation in response thereto, means. to detect the characteristic X-radiation produced by said element, and means coupled to said detection means andi responsive to the intensity of the characteristic radiation produced by said element for controlling the potential of said" source. 7

3. .A device for controlling the potential of a source comprising an X-ray tube coupled to said source, a secondary radiator exposed to primary X-radiation produced by said tube and'containing a first element whichgenerates its characteristic X-radiation in response thereto, a second secondary radiator exposed't'o said X-radiation and'adapted'only to scatter primary X-radiation incident thereon, means to detect the X-radiation obtained'j from said secondary radiators,'and means coupled to said de-,

tection means and responsive to the intensity of the X- radiation produced by said secondary radiators for cona second specimen having an atomic number different;

than and adapted only to scatter primary X-radiation incident thereon, means to detect and produce an electrical quantity-corresponding to the'intensity of the characterise tic X-ray radiation produced by said first secondary radiator, means to detect and produce an electricaljquantity proportional to the intensity of the primary radiation scattered by said second secondary radiator, means coupled to both of said detection 'means for. obtaining an electrical quantity proportional to the difierence besource tween the electrical quantities produced by said first and secondidetection means, and means coupled to said dif ference producing means andsaid source'for controlling the potential thereof. Q

5. A device for controlling the potential of a source comprising an X-ray tube coupled to said'source, a secondary radiator exposed'to primary X-radiation produced by said tube andcontaining an element which generates its characteristic X.- ray spectrurn'in response tosaid primary radiation, a second secondary radiator containing an element having 'an atomic numberhigher than said 7 first element and adapted only to scatter primary-X-radiation incident thereon, means to detect and produce an electrical quantity corresponding tofthe; intensity of the Q characteristic X-ray radiation produced by said first secondary radiator, means to detect and, producetan elec:

trical quantity proportionalto the intensity of the priv mary radiation scattered by said second. secondary radiator, means coupled to both of saidldetection meansffor obtaining an electrical quantity proportional: to the; difference between the electrical quantities producedlby, said. first andsecond' detection means and means coupled to; 7 said difierence producing means and saidsource for con? trolling-the potential thereof.

References Cited in the fiie of this, patent 7 UNITED STATESPATENTS.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,836,727 May 27, 1958 Herbert Friedman It is herebj certified that error appears in the printed specification of the above. numbered patent requiring correction and that the said Letters Patent should read asv corrected below.

Column 3 lines 20, 21 and 22 strike out a second specimen having an atomic number different than",-

Signed and sealed this 29th day of July 1958(,

(SEAL) Attest; KARL I-L, AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

